Life is sacred. It remains sacred even after death. When death is hastened it is to say that at some point life is not worth living. I as a Christian can never accept this and will never. I believe we have to do all we can to make a person as comfortable as possible while they are on this planet.
The idea of consciously deciding whether life is so uncomfortable that it should be ended says that life on this planet is all there is. It says that we humans believe we can play God. It says that there is no God. And it says that the experiences that we came here to have can be cut short if they become inconvenient.
If you an do that for the unfortunate you can do that for an unborn baby or a person who is consdiered unfit to live here.